Madbouly, S. A., Wolf, B. A.

"Crystallization Kinetics of Polyethylene Oxide from its Melt and from Mixtures with Tetrahydronaphthalene and Oligo(Ethylene Oxide-block-Dimethylsiloxane)"

Journal of Polymer Science Part B: Polymer Physics 2004, 42, 820-829.

Abstract: The crystallization of poly(ethylene oxide) (PEO) from the pure state and from its mixtures with oligo(dimethyl siloxane-b-ethylene oxide) (COP) and tetrahydro-naphthalene (THN) has been investigated. The crystallization kinetics was studied isothermally and non-isothermally using an automated device that monitors the light passing through the corresponding liquids as functions of time and/or temperature. The rate was found to be strongly influenced by the concentration of COP in the mixture. A substantial decrease in the induction time, t0 (the time required for the onset of crystallization) and a considerable shift in the crystallization temperature (TL/S transition from liquid to solid state) to higher temperatures have been observed as the concentration of COP rises. This behavior is attributed to the difference in the interaction parameters of PEO with THN or COP. The isothermal crystallization kinetics was analyzed on the basis of the Avrami equation. Modified approaches (Avrami and Ozawa) have been used for the evaluation of non-isothermal crystallization. In the initial state of crystallization a power law holds true for the augmentation of the radii of spherulites with time for all mixtures regardless of the concentration of COP. Different spherulitic morphologies are observed depending on the COP concentration. With rising COP content the structures change from needle-like to compact. The present findings are above all discussed in terms of the isothermal variation of the degree of super-cooling resulting from changes in the composition of the mixture

preprint number: 241